守护线程的案例

Author: BYSocket

src/org/javacore/thread/daemon/CleanerTask.java

@@ -0,0 +1,52 @@
+package org.javacore.thread.daemon;
+
+import java.util.Date;
+import java.util.Deque;
+
+/**
+ * 描述:管理这个队列,如果事件超过10秒钟,就会被移除
+ * Created by bysocket on 16/3/4.
+ */
+public class CleanerTask extends Thread{
+    private Deque<Event> deque;
+
+    public CleanerTask(Deque<Event> deque) {
+        this.deque = deque;
+        setDaemon(true);
+    }
+
+    @Override
+    public void run() {
+        while (true) {
+            Date date = new Date();
+            clean(date);
+        }
+    }
+
+    /**
+     * 删除该时间前10s内创建的事件对象
+     * @param date
+     */
+    private void clean(Date date) {
+        long difference = 0;
+        boolean delete;
+        if (deque.size() == 0) {
+            return;
+        }
+        delete = false;
+
+        do {
+            Event e = deque.getLast();
+            difference = date.getTime() - e.getDate().getTime();
+            if (difference > 10000) {
+                System.out.printf("Cleaner: %s \n",e.getEvent());
+                deque.removeLast();
+                delete = true;
+            }
+        } while (difference > 10000);
+
+        if (delete) {
+            System.out.printf("Cleaner: Size of the queue: %d\n",deque.size());
+        }
+    }
+}

src/org/javacore/thread/daemon/DaemonTest.java

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+package org.javacore.thread.daemon;
+
+import java.util.ArrayDeque;
+import java.util.Deque;
+
+/**
+ * 1. 知道3个WriteTask线程休眠后,CleanerTask才执行
+ * 2. 从结果中,可以看出队列维持在一定数量当中
+ * Created by bysocket on 16/3/4.
+ */
+public class DaemonTest {
+    public static void main(String[] args) {
+        Deque<Event> deque = new ArrayDeque<>();
+        WriterTask writerTask = new WriterTask(deque);
+        for (int i = 0; i < 3 ; i++) {
+            Thread thread = new Thread(writerTask);
+            thread.start();
+        }
+
+        CleanerTask cleanerTask = new CleanerTask(deque);
+        cleanerTask.start();
+    }
+}

src/org/javacore/thread/daemon/Event.java

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+package org.javacore.thread.daemon;
+
+import java.util.Date;
+
+/**
+ * 描述:事件类
+ * Created by bysocket on 16/3/4.
+ */
+public class Event {
+    private Date date;
+    private String event;
+
+    public Date getDate() {
+        return date;
+    }
+
+    public void setDate(Date date) {
+        this.date = date;
+    }
+
+    public String getEvent() {
+        return event;
+    }
+
+    public void setEvent(String event) {
+        this.event = event;
+    }
+}

src/org/javacore/thread/daemon/WriterTask.java

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+package org.javacore.thread.daemon;
+
+import java.util.Date;
+import java.util.Deque;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * 描述:写事件到一个队列
+ * Created by bysocket on 16/3/4.
+ */
+public class WriterTask implements Runnable {
+    private Deque<Event> deque;
+
+    public WriterTask(Deque<Event> deque) {
+        this.deque = deque;
+    }
+
+    @Override
+    public void run() {
+        for (int i = 1; i < 100; i++) {
+            Event event = new Event();
+            event.setDate(new Date());
+            event.setEvent(String.format("The thread  %s has generated an event",Thread.currentThread().getId()));
+            deque.addFirst(event);
+
+            try {
+                TimeUnit.SECONDS.sleep(1);
+            } catch (InterruptedException e) {
+                e.printStackTrace();
+            }
+        }
+    }
+}